Saturday, April 11, 2009

status updates

Sorry I haven't had much time to write here... I've been up working on the bots every day this break from 9 or 10 in the morning until 12, 1, 2AM... It's been a long week but things are finally coming together.

COPPERHEAD
Copperhead is being assembled for the last time (thank god, cause it takes about 2 hours...). We painted the frame and shaft clamps an extra-flat black. It looks really cool. The drum is also freshly painted a very shiny copper. As we all know, the pretty paint won't be pretty by the end of the competition, but at least we'll look good for photos when we get there. :P
We've been having some issues with very temperamental electronics... We've got a Victor 883 for each drive motor, and a Thor 883 for the weapon. AIL/ELE are mixed with a mixer/booster chip, and we're using a signal driver cable for the weapon. The driver cables are SO BAD! We have three and they work sporadically! I don't get it! I'm contemplating just going all out and dropping $35 on a booster chip and just regular 12 inch cables (since we certainly don't need the 36" ones we have... :P). The other problem we're running into is on one of our motors, I think the back emf from it is interfering with the mixer chip, so the radio signal becomes intermittent when that motor is running - to the point where it loses signal, then doesn't come back until you reset power to the bot. But ONLY the mixer is affected. The weapon never loses signal. It's really odd. I'm trying to contact a friend of ours who lives close by to see if we can borrow an end cap from him that could potentially have good RF-suppression capacitors in it (if ours are bad and that's the problem...). All our testing concluded that the MOTOR was the problem, not any of the electronics. I don't know. Hopefully we'll figure it out. The drum still spins beautifully, and actually maxed out at 3453 RPM when we tested it. A far cry from our purported 4900, but nonetheless impressive. If we do the math... it comes out to a tooth-tip speed of 88 mph. Our weight (when we checked yesterday - it was missing a few small things) was 119.50 lbs.

DETHINATOR
The Dethinator actually works! The spin-up time is impressive, and our final RPM is pretty impressive too, 2200 RPM. Alan is learning how to drive it for San Francisco. We need to come up with a safety device and locking mechanism, so it's not quite as crappy as Miami was. I made a shunt resistor to measure current draw, and we figured out at the beginning of Thursday that the inrush of current (with the shell on) was over 130 A, and it settled around 60-70A to hold max speed. The battery is only rated for a max continuous discharge of 60A, so this explains why it was getting hot. We put the flux rings back on the motors (my bad... :P) and this greatly improved their performance and decreased the temperature that they were running at. We also put air scoops on the top to push air through the holes. This will keep everything much cooler as well and shouldn't have TOO big an impact on our RPM. Hopefully we'll be good to go for San Fran, but we're bringing a bunch of extra motors just in case. Final weight - 14.90 lbs


THE CRATE/SHIPPING
We are almost done building our crate (we just need to make the top piece and then we'll be set to go). We pack it up tomorrow, so any changes we need to make to the bots needs to be done by tomorrow. I need everyone's stuff to ship who is going to San Francisco. I'll call everyone today to figure out when to pick up/when you can bring it to us (the better option!).. We have a slight shipping fiasco however because we were gonna do one thing, somebody promised us a better price, then we cancelled the first thing, then the better price guy realized he was talking to a complete IDIOT at UPS who was quoting him for one-way prices or something like that, so we had to uncancel plan A... it's a mess.









So yeah. That is our status.
More videos to come.

1 comment:

Alan Dreher said...

Update: Safety device for Dethinator is done and we have decided that Brian is going to be the Safety/Pool Noodle Handler for Dethinator in San Francisco. It is pretty simple to do everything, and mostly self explanatory, but there is some definitely procedure that we will need to go over.